Add query-aware search policies

[jolestar]

Summary

• add optional search.policy.shortQuery and search.policy.longQuery on top of site-level search defaults
• resolve search options in mdorigin based on trimmed query length while keeping /api/search limited to q, topK, and meta.*
• document dynamic policy behavior, including null overrides that explicitly clear inherited defaults

Testing

• npm run check
• npm test

Closes #26

[Copilot]

Pull request overview

Adds a query-aware “policy” layer to mdorigin’s search configuration so retrieval behavior can vary for short vs long queries, while keeping the public /api/search surface limited to q, topK, and meta.* filters.

Changes:

• Introduce search.policy.shortQuery / search.policy.longQuery config (with null to explicitly clear inherited defaults) and normalize it in site config loading.
• Resolve effective search options per request based on trimmed query length (Unicode code points), with shortQuery taking precedence when thresholds overlap.
• Add tests and documentation covering dynamic policy behavior and precedence rules.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
src/search.ts	Adds policy-aware option resolution and applies it across SearchApi implementations.
src/search.test.ts	Adds integration tests validating long/short policy selection and null clearing behavior.
src/core/site-config.ts	Extends and normalizes site search config to support query-aware policy entries.
src/core/site-config.test.ts	Verifies policy normalization (including null overrides) during config loading.
skills/mdorigin/SKILL.md	Notes that sites can configure query-aware search policies.
docs/site/reference/configuration.md	Documents policy keys, matching rules, and null clearing semantics with an example.
docs/site/guides/getting-started.md	Adds getting-started guidance and example config for dynamic search policy.

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[Copilot]

SiteSearchLongQueryPolicyConfig and SiteSearchShortQueryPolicyConfig are imported but never used in this file. Removing unused type imports will keep the module clean and avoids future lint/CI failures if unused-import checks are added.

Suggested change

	SiteSearchLongQueryPolicyConfig,
	SiteSearchPolicyOverrideConfig,
	SiteSearchRerankerConfig,
	SiteSearchShortQueryPolicyConfig,
	SiteSearchPolicyOverrideConfig,
	SiteSearchRerankerConfig,